Cathodic protection system and minaturized constant current rectifier

ABSTRACT

A cathodic protection system providing substantially complete coverage to individual steel-in-concrete units in a multi-unit structure. The system includes a power supply, an electronic circuit board, a header cable, anode wire in each unit connected to the header cable, an adhesive connector in each unit, and a conductor in each unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This continuation application claims the benefit of non-provisional U.S.patent application Ser. No. 16/297,982 filed Mar. 11, 2019, which ishereby incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION

The subject matter herein relates generally to cathodic protectionsystems and more particularly to cathodic protection systems forsteel-in-concrete structures utilizing a constant current rectifier witha voltage limiter.

In order to protect steel-in-concrete structures, primarily including,but not necessarily limited to, individualized balconies on condominiumor apartment-style units, from cracking, various cathodic protectionsystems have been utilized. In all such systems, an anode or a string ofanodes is either laid on the concrete or embedded in it. The anodes areconnected in a circuit containing a rectifier and the steel reinforcingbars. The current from the rectifier is sent through the circuit wiringto the anode at which point it passes through the concrete itself to thereinforcing bars and from there through a negative return cable to therectifier.

One type of cathodic protection system is sometimes referred to as anoverlay system. That system comprises disposing a plurality of flexiblyinterconnected anodes on the concrete deck or base to be protected andcementing them in place. That system basically consists of applying aconductive paint completely over the surface of the concrete layercontaining the reinforcing bars. Thereafter, preferably, a series ofsmall diameter platinum wires are attached to the concrete paint layerutilizing, e.g., strips of self-adhesive fiberglass mesh tape. The meshis then covered with a layer of conductive paint. The anode system iscompleted and covers the entire concrete surface excluding a smallradius around metal; typically, 2 inches in diameter and one inch fromthe edges. A cosmetic acrylic paint can then be put over the conductivepaint. The anodes are connected to a rectifier controller through aheader cable.

A need to provide constant, individualized current to each balcony hasproven to be necessary for a combination of reasons. The traditionalmethod using the typical cathodic protection rectifier uses a designedamount of protective current supplied to all the combined unit areas. Ina residential condominium-style structure consisting of many exclusiveuse units, the cathodic protection rectifier method may: oversupplyprotective current to some exclusive balcony units, undersupplyprotective current to other exclusive balcony units, or supply noprotective current to a number of exclusive balcony units.

There is no way to decipher whether all the unit balconies are receivingthe design current or any protective current at all. An oversupply ofcurrent results in the burning of the anode, causing separation of theanode from the concrete—resulting in little ongoing protection. Anundersupply of current or no supply of current allows for the corrosionto continue. Given these issues, there exists a need for customizablecurrent protection without destructive testing. The disclosed inventionachieves this goal by having an adjustable rectifier installed into eachcondominium receptacle area, where the direct current supplied to a unitvaries according to the specific need of each such unique unit.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, a cathodic protection system utilizing a miniaturizedconstant current rectifier is provided. In the preferred embodiment, thesystem includes a power supply, electronic board converter, headercable, anode wire, and conductive transmitter, typically a conductivecoating.

The miniaturized constant current rectifier preferably includes a powersupply, an electronic circuit board to convert residential AC 120 V toDirect Current, and an electronic circuit board to adjust the output ofDirect Current and to limit the voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the reinforcing steel mat in a concrete balconyslab.

FIG. 2 is an elevation view of the reinforcing steel mat in a concretebalcony slab.

FIG. 3 shows the AC power, rectifier, header cable, and anode wireplacement.

FIG. 4 shows placement of an adhesive fiber mat over an anode wire tohold it in place for painting of a concrete slab, anode wire, and tape.

FIG. 5 shows the system portrayed without electrical wiring.

FIG. 6 is a flowchart of the entire cathodic system according to anembodiment.

FIG. 7 is a flowchart of the miniaturized constant current rectifieraccording to an embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description illustrates the claimed invention byway of example and not by way of limitation. The description clearlyenables one skilled in the art to make and use the invention, describesseveral embodiments, adaptations, variations, alternatives, and uses ofthe claimed invention, including what is presently believed to be thebest mode of carrying out the claimed invention. Additionally, it is tobe understood that the claimed invention is not limited in itsapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in thedrawings. The claimed invention is capable of other embodiments and ofbeing practiced or being carried out in various ways. Also, it is to beunderstood that the phraseology and terminology used herein is for thepurpose of description

As shown in FIGS. 1-6, the cathodic protection system 100 of theinvention is designed specifically to provide customizable constantcurrent to individualized balcony condominium-style or similar typeunits 10. The system utilizes a state of the art miniaturized constantcurrent rectifier (See FIG. 7) to ensure complete coverage.

Referring to an embodiment illustrated in FIGS. 3-5, the rebar 4 isplaced at approximately ¾″ below the surface of the concrete 6 in thereinforcing steel mat 20. Anode wire 8 is placed in a 1/16″ groove 12cut into the concrete 6 for aesthetic reasons or directly on top of theconcrete surface. An adhesive fiber mat 14 is placed over the anode wire8 holding the wire in place so that conductive paint 16 can be added.

The power supply 18 includes a header cable 22 which supplies DirectCurrent.

As known to those who work in this field, a standard sized cathodicprotection system is typically designed to protect up to fortybalconies. Its cabinet, an integral piece of the total rectifying unit,usually measures 1.5 ft. deep×2 ft. wide×3 ft. high, or a total of 9cubic ft. of space. Moreover, given their standardized features, thecathodic protection unit cannot effectively be made smaller no matterthe number of balconies to be protected. Referring to FIG. 7, in anembodiment depicted therein, the miniaturized constant current rectifier(MCCR) 30 operates from Component Block A 32, AC wall power (85 VAC to265VAC at 50Hz or 60Hz, European or American power). The Component BlockB is an AC to DC converter 34 with sufficient power capability todeliver the appropriate power (voltage and current) to the ComponentBlock C Constant Current Control Circuit 36. Such a miniaturized unit,designed to effectively protect an individual unit, only occupies @ 0.15cubic ft., i.e., around 60× smaller that a standard cathodic protectionrectifier which can fit into a half cell concrete block (8″×8″×8″).

Component Block B 34 typically uses (but is not limited to) common AC toDC conversion topologies such as switch-mode power supply (SMPS), ACOffline Switcher, Buck Converter, Fly Back, Fly Forward, continuousconduction, discontinuous conduction, step down transform and full orhalf bridge rectifier, AC to DC wall wart type. Component Block B istypically transformer isolated with a low voltage DC output for safety.Component Block B typically outputs insulated low voltage DC electricalpower (such as 3.3V, 5V, 9V, 12V, 15V, 24V) for consumer safety, but itis not limited to low voltage DC electrical power.

Component Block C Constant Current Control Circuit 36 is responsible foraccepting the input power (typically low voltage DC electrical power)and providing constant protective current to Component Block D CathodicProtective Assembly. In cases where Component Block B is providing powerother than low voltage DC, Component Block C has the capability toconvert such power back into electrical current such as via anadjustable current potentiometer. From an electrical circuitperspective, Component Block D Cathodic Protective assembly 40 behavesas a variable electrical impedance/resistance based on the chemicalreactions between the rebar, concrete and the coating. As the electricalimpedance/resistance changes over time in Component Block D, theConstant Current Control Circuit will maintain the same current flowing.The voltage will adjust accordingly as the impedance/resistance of BlockD changes. The voltage adjustment is used as a limiter to fail-safe tocurrent flow. The adjustable voltage limiter is set at a valueapproximately no greater than, preferably 20-30% higher than theoperating voltage. The operating voltage can be determined by therequired voltage to maintain the desired current.

The exact implementation of the Constant Current Control Circuit can bevaried (e.g., DC to DC converter, Buck, Boost, Boost-Buck, CUK, Linearcurrent regulation, Current Mirror, etc.) so long as the device suppliesa constant (stable) current at a desired level even though the impedanceof the cathodic protective assembly changes. Examples of materialchanges may include, among other factors, changes in ambienttemperature, salt intrusion, rain, dry season, wet season, winddirection, concrete chemistry change, etc. The Constant Current ControlCircuit has the capability to manually adjust the current to account forvarious cathodic protective assemblies that are to be protected (e.g.,in a concrete pad with rebar, the current requirements may beapproximately in the range of 0.5 mA to 2 mA per square feet). As aprotective feature, the constant current control circuit has anadjustable maximum voltage output. As the concrete cures, theimpedance/resistance changes, usually decreasing with time; the rebarpotential changes and usually less current flow is required forprotection. Once the maximum (limiting) voltage is reached, the constantcurrent control circuit automatically switches from constant currentregulation to constant voltage regulation as an overprotection device.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. A cathodic protection system for providingsubstantially complete, individualized balcony-unit style coverage to amulti-unit structure featuring separate steel-in-concrete units, thesystem comprising: a power supply, an electronic circuit board, a headercable to carry current, anode wire in each unit connected to the headercable, an adhesive connector in each unit, and a conductor on each unit.2. The system of claim 1 wherein the structure comprises asteel-in-concrete, multi-balcony condominium or apartment-stylestructure.
 3. The system of claim 1 wherein the electronic circuit boardis configured to convert residential AC 120 V to Direct Current atapproximately 2 mA per square foot of concrete.
 4. An apparatus forproviding miniaturized constant current protection comprising: a powersupply, a first electronic circuit board configured to convertresidential AC 120 V to Direct Current, and a second electronic circuitboard configured to adjust the output of Direct Current and provide theminiaturized constant current protection.
 5. A method of providingsubstantially complete, individual unit coverage to a multi-unitstructure comprising individual condominium-style steel-in-concretebalcony-style units, the method comprising: activating a cathodicprotection system comprising a power supply, an electronic circuitboard, a header cable to carry current, anode wire to each unit whereprotection is sought, connected to the header wire, an adhesive in eachunit where protection is sought, and a conductor applied to each suchunit; activating the cathodic protection system to provide constantcurrent protection by application of an apparatus comprising a powersupply, a first electronic circuit board to convert residential AC 120 Vto Direct Current, and a second electronic circuit board to adjust theoutput of Direct Current.
 6. The method of claim 5 wherein the secondelectronic circuit board is configured to provide miniaturized constantcurrent protection to the individual condominium-style steel-in-concretebalcony-style units.
 7. The method of claim 5 further comprising firstinstalling the cathodic protection system of claim
 5. 8. The method ofclaim 5 further comprising adjusting the output of Direct Current byutilizing the second electronic circuit board, thereby customizing thecurrent protection of individual units.